Preference for Facial Symmetry Depends on Study Design

Anthony J. Lee,Jessica K. De La Mare,Hannah R. Moore,Pamela C. Umeh

doi:10.3390/sym13091637

Abstract

Facial symmetry is purportedly attractive, though methods for measuring preference for facial symmetry vary between studies. Some studies have used a two-alternative forced choice (2AFC) task, while others have used a ratings task. How researchers manipulate facial symmetry also varies; some studies have used faces manipulated to be more (or perfectly) symmetrical, while others have used faces manipulated to be more asymmetrical. Here, across three studies, we evaluate and compare these different methods. In Studies 1 and 2 (N = 340 and 256, respectively), we compare facial symmetry preferences as measured by the 2AFC and ratings tasks. Across both studies, we consistently found a significant preference for facial symmetry when using the 2AFC task, but not with the ratings task. Additionally, correlations between facial symmetry preferences as measured by the two tasks were weak or showed no association. In Study 3, 159 participants rated the attractiveness of faces manipulated to be either symmetrical or more asymmetrical. The asymmetrical faces were rated as significantly less attractive compared to the original faces, while the difference in attractiveness ratings between the original and symmetrical versions was comparatively much smaller. These studies suggest that preference for facial symmetry depends greatly on the study design.

Highlights

Facial symmetry is purportedly attractive, though methods for measuring preference for facial symmetry vary between studies
Given a strong effect was found here, while only a small effect was found in Study 1, this supports the notion that symmetry preferences may not be linear, and instead effects are stronger when original faces are paired with more asymmetrical versions compared to symmetrical versions
For both males rating female faces and females rating male faces, we found a significant difference in attractiveness ratings between the original and asymmetrical versions

Summary

Introduction

Facial symmetry is purportedly attractive, though methods for measuring preference for facial symmetry vary between studies. Participants are presented with faces sequentially and asked to rate how attractive they find each face on a numeric scale (e.g., a 7-point scale where 1 = unattractive, and 7 = attractive) In this task, faces are either manipulated to be more/less symmetrical (e.g., [14,15]), or natural variation in facial symmetry is measured in unmanipulated faces (e.g., [16,17,18]). Jones and Jaeger [19] reported divergent results when using both tasks, where a statistically significant preference for perfectly symmetrical faces was found when using a 2AFC paradigm, but no significant preference was found when participants completed a ratings task This is consistent with a recent, large scale study using a ratings task with naturally varying faces that failed to find a preference for facial symmetry [20]. Lewis [22] suggested that the 2AFC task may instead measure the ability of participants to detect asymmetry in faces rather than a preference for symmetrical faces per se; this is an important distinction as ability to detect asymmetry does not necessarily indicate a preference for symmetry [23,24]

Methods

Results

Conclusion